The present invention relates to pumps, and particularly to pumps useful in respirator apparatus. The invention also relates to an exhalation valve assembly useful in such pumps and respirator apparatus. Respirator apparatus, sometimes called ventilator apparatus, is widely used for administering artificial respiration or ventilatory assistance to a patient. Examples of such apparatus are described in my prior U.S. Pat. Nos. 4,807,616, 4,823,787 and 4,941,469.
An object of the present invention is to provide a novel pump particularly useful in respirator apparatus and providing a number of important advantages as will be described more particularly below. Another object of the invention is to provide an exhalation valve assembly also particularly useful in the novel respirator apparatus.